The SPP-1 underwater pistol was made in the Soviet Union for use by Soviet frogmen as an underwater firearm. It was developed in the late 1960s and accepted for use in 1975. Under water, standard bullets are inaccurate and have very short range. This pistol instead fires a round-based 4.5 millimetres (0.18 in) caliber steel dart about 115 millimetres (4.5 in) long, weighing 12.8 grams (0.45 oz), which has longer range and more penetrating power than a speargun. The complete cartridge is 145 millimetres (5.7 in) long and weighs 17.5 grams (0.62 oz).

The SPP-1 has four barrels, each containing one cartridge. Its ammunition comes as a magazine of four cartridges which is inserted into the pistol's breech.

Its barrel is not rifled; the fired projectile is kept in line by hydrodynamic effects. As a result, it is somewhat inaccurate when fired out of water.

A double-action firing mechanism fires one cartridge sequentially for each pull of the trigger. When all four cartridges are spent, the gun can be reloaded above or below water.

The SPP-1M pistol is essentially the same as the SPP-1, with the following differences:

The weapon was designed by Vladimir Simonov, the cartridge by Pyotr Sazonov and Oleg Kravchenko. Simonov also designed the APS amphibious rifle.

Depth reduces range because the higher pressure closes the cavity sooner. Once the projectile is no longer supercavitating, hydrodynamic drag increases greatly, and the projectile becomes unstable.

Lethal range is defined as the range from which it can easily penetrate a padded underwater suit or a 5 millimetres (0.20 in) thick glass faceplate.